Our invention relates generally to an apparatus having a data transducer (head) or transducers for data transfer (writing and/or reading) with a replaceable, rotating disk such as a flexible magnetic disk rotatably enclosed in a stiff jacket or housing to make up a disk cartridge. More particularly, our invention deals with a system in such a rotating disk data storage apparatus for preventing a stepper motor or like transducer positioning motor from moving the transducer or transducers when the disk is not loaded in the apparatus.
The flexible magnetic disk drive has found extensive use as a data storage device on small computing systems. We cite Kitahara et al. U.S. Pat. No. 4,604,666, assigned to the assignee of our present application, as a typical prior art disk drive pertinent to our invention. In this and other familiar disk drives, a pair of data transducers are provided for writing and/or reading data on both sides of the disk. Both transducers are moved across a multiplicity of concentric annular data tracks on the disk surfaces by a bidirectional electric motor such as a stepper motor. One of the transducers, moreover, which is mounted on a pivoted support beam, is movable away from the other for permitting the disk to be loaded in a preassigned data transfer position within the disk drive. The disk is caught between the transducers after having been placed in the data transfer position.
The current trend in disk drives is toward the minimization of their thickness or vertical dimension. In making this statement we assume that the disk is disposed horizontally in the data transfer position, with the pair of transducers disposed above and below the disk. The above objective inherently requires that the upper transducer be positioned as close as possible to the top plate of the casing of the disk drive, or to a shield plate or a printed circuit board if either of these is provided just under the top plate.
It may be contemplated, then, to hold the support beam, carrying the upper transducer, against the top plate, or to any other essentially equivalent part, when the upper transducer is moved away from the lower. This scheme is certainly advantageous purely from the standpoint of thickness reduction of the disk drive. However, if incorporated in prior art disk drives, it will bring about some inconveniences.
Conventionally, the stepper motor has been free to rotate in response to external stepping pulses from a host system even when the disk is not loaded in the disk drive. Also, the stepper motor has been driven by internal stepping pulses for recalibration, that is, for positioning the transducers over Track Zero on the disk, when the disk drive is electrically powered on, even if the disk is then not yet loaded therein. Since the upper transducer is held away from the lower when the disk is not loaded, the support beam would then travel in sliding contact with the top plate or the like, producing unpleasant noise. The support beam would also suffer abrasion as a result of the repetition of such sliding movement over an extended period of time.
Such inconveniences have also been liable to occur even if the transducer support beam is designed to make no contact with the top plate or the like. The support beam has nevertheless been easy to come into contact with the top plate or the like in the course of time, due for example to the deformation or displacement of a stop member, or of any other part associated therewith, for limiting the pivotal movement of the support beam.